Radio News, July, 1922, page 55:
 U.S. Radio Inspection Districts Map - July, 1922

In late 1912, the Department of Commerce and Labor's Bureau of Navigation divided the United States into nine "Radio Inspection Districts", in order to enforce provisions of the August 13, 1912 "Act to Regulate Radio Communication". The layout of the districts reflected the early emphasis on radio's use by seagoing vessels. Except for a few minor adjustments, the overall district boundaries were still the same in 1922.
The August 15, 1919 edition of Radio Communication Laws of the United States, included the following description of the Radio Inspection Districts:

163. The Department has established, for the purpose of enforcing, through radio inspectors and others, the acts relating to radio communication and the International Convention, the following districts, with the principal office for each district at the customhouse of the port named.

  1. BOSTON, MASS.: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut.
  2. NEW YORK, N. Y.: New York (county of New York, Staten Island, Long Island, and counties on the Hudson River to and including Schenectady, Albany, and Rensselaer) and New Jersey (counties of Bergen, Passaic, Essex, Union, Middlesex, Monmouth, Hudson, and Ocean).
  3. BALTIMORE, MD.: New Jersey (all counties not included in second district), Pennsylvania (counties of Philadelphia, Delaware, all counties south of the Blue Mountains, and Franklin County), Delaware, Maryland, Virginia, District of Columbia.
  4. SAVANNAH, GA.: North Carolina, South Carolina, Georgia, Florida, Porto Rico.
  5. NEW ORLEANS, LA.: Alabama, Mississippi, Louisiana, Texas, Tennessee, Arkansas, Oklahoma, New Mexico.
  6. SAN FRANCISCO, CALIF.: California, Hawaii, Nevada, Utah, Arizona.
  7. SEATTLE, WASH.: Oregon, Washington, Alaska, Idaho, Montana, Wyoming.
  8. DETROIT, MICH.: New York (all counties not included in second district), Pennsylvania (all counties not included in third district), West Virginia, Ohio, Michigan (Lower Peninsula).
  9. CHICAGO, ILL.: Indiana, Illinois, Wisconsin, Michigan (Upper Peninsula), Minnesota, Kentucky, Missouri, Kansas, Colorado, Iowa, Nebraska, South Dakota, North Dakota.

(Until mid-1919 the 8th radio district had been headquartered in Cleveland, Ohio).